Grand River Streambank Restoration

摘要

The banks of the Grand River, a State-designated Wild and Scenic River in northeast Ohio's Lake County, are naturally steep. However, the manmade banks within this 3,100 foot project reach consist of 20 foot tall constructed clay dike walls with a slope of 1.5:1 (H:V) or steeper that were created almost a century ago to hold process residuals from Solvay soda ash manufacturing. This site is being redeveloped and will ultimately include amenities such as a sports training facility and world-class golf course, luxury homes, a vineyard and a trout club. As part of this process, the existing banks were replaced with less steep, stable slopes with native vegetation typical of the river corridor. The streambank restoration also incorporated a bench for improved slope stability that will serve as a walking path to increase public access to the Grand River's beautiful scenery and extraordinary steelhead trout fishery. The naturalization of this artificial streambank and the incorporation of access will increase the value of this area for both the public and the environment and assist this formerly industrial site in finding new life as a luxury development. Civil and geotechnical engineers and ecologists collaborated in the design effort and coordinated with the construction coordinator to implement these streambank improvements. As part of this design-build project, the Grand River's local ordinary high water mark was identified, a slope stability analysis was performed, the streambank cross-section and pathway design were developed, and specifications for native vegetation that serves as permanent erosion control were prepared. This multidisciplinary approach resulted in a project that effectively addresses the need for a stable slope in a manner that enhances the river corridor and returns this reach to a more natural state. Project coordination included communication with the Army Corps of Engineers, the Ohio EPA, and the Lake County MetroParks to obtain their input and approval, as needed. The streambank construction occurred from November 2006 through February 2007, with temporary erosion control measures, including a diversion berm along the top of the slope and flexible growth medium with temporary seeding hydraulically applied over the entire slope, and sedimentation controls at the toe of the slope being incorporated throughout the construction process. Permanent erosion control, including installation of coir fabric and live staking within the 100-year floodplain and grass and forbs seeding over the entire slope, was installed from March through May 2007.